In Swedish Patent Application No. 8902335-2 a method and a device is described for producing a shock wave by means of a compressed air cannon to unstick deposits on fan impeller blades. This technique is applicable to fans used under heavy environment conditions, like in dusty spaces such as in kilns of cement plants where deposits of dust on the impellers can cause severe vibration problems. FIG. 1 shows an example of a device according to this prior art with a compressed air cannon disposed at the fan inlet.
In some applications the hardness of the deposits on the blade surfaces will be so high that the deposits can not be efficiently removed by pulses of compressed air.